>> help punct
 Punctuation.
  .   Decimal point. 325/100, 3.25 and .325e1 are all the same.
 
  .   Array operations.  Element-by-element multiplicative operations
      are obtained using .* , .^ , ./ , .\ or .'.  For example,
      C = A ./ B is the matrix with elements c(i,j) = a(i,j)/b(i,j).
 
  .   Field access.  A.field and A(i).field, when A is a structure, access
      the contents of the field with the name "field".  If A isn't a
      scalar structure, this produces a comma separated list (see LISTS).
      You can nest structure access as in X(2).field(3).name.  You can
      also combine structure, cell array, and parentheses subscripting 
      for arrays stored in the structure (see PAREN).
 
  ..  Parent directory.  See CD.
 
  ... Continuation. Three or more periods at the end of a line continue 
      the current command or function call onto the next line. Three or 
      more periods before the end of a line cause MATLAB to ignore the 
      remaining text on the current line and continue the command or 
      function call onto the next line. This effectively makes a comment 
      out of anything on the current line that follows the periods.
 
  ,   Comma.  The comma is used to separate matrix subscripts
      and arguments to functions.  It is also used to separate
      statements in multi-statement lines. In this situation,
      it may be replaced by a semicolon to suppress printing.
 
  ;   Semicolon.  The semicolon is used inside brackets to indicate
      the ends of the rows of a matrix.  It is also used after an
      expression or statement to suppress printing.
 
  %   Percent.  The percent symbol is used to begin comments.
      Logically, it serves as an end-of-line character.  Any
      following text on the line is ignored or printed by the
      HELP system.
 
  %{  Percent-OpenBrace.  This symbol begins a block comment. Use this
      symbol to enter a multiline comment. MATLAB ignores everything
      within a block comment during execution including any program code.
      The %{ symbol must appear alone on the line that precedes the comment.
 
      You can also use block comments to comment out code in the middle 
      of a multi-line statement. You cannot do this with the single-line 
      comment operator, %. For example, the statement on the left below 
      is valid, while the one on the right is not:
 
             addpath(...               addpath( ... 
                 'dir1', ...               'dir1', ... 
             %{                        %    'dir2', ...
                 'dir2', ...               'dir3'
             %}                            )
                 'dir3' ...
                 )
 
  %}  Percent-CloseBrace.  This symbol ends a block comment. Use this
      symbol to enter a multiline comment. MATLAB ignores everything
      within a block comment during execution including any program code.
      The %} symbol must appear alone on the line that follows the comment.
      See the %{ symbol, above.
 
  !   Exclamation point.  Any text following the '!' is issued
      as a command to the underlying computer operating system.
      On the PC, adding & to the end of the ! command line, as in
         !dir &
      causes the output to appear in a separate window and for the window
      to remain open after the command completes.
 
  '   Transpose.   X' is the complex conjugate transpose of X. 
      X.' is the non-conjugate transpose.
 
  '   Quote. 'ANY TEXT' is a vector whose components are the
      ASCII codes for the characters. A quote within the text
      is indicated by two quotes.  For example: 'Don''t forget.'
 
  =   Assignment.  B = A stores the elements of A in B.
 
  @   At.  The at symbol is used to create a function_handle.
      It is also used at the beginning of directory names that contain
      matlab object methods and the constructor for the object, e.g.
      the directory @inline contains the constructor inline.m for the 
      inline object and all methods for inline objects.
 
  ~   The tilde character can be used in function definitions to
      represent an input argument that is unused within the function.
      It can also be used to indicate that an output argument of a
      function call is to ignored.  In this case, it must appear
      within [ ] and separated by commas from any other arguments.
 
 
      See also relop, colon, lists, paren, cd, function_handle.